This application claims priority of Korean Patent application No. 98-15083 filed on Apr. 28, 1998, the disclosure of which is incorporated herein by reference.
1) Field of the Invention
The present invention relates to a liquid crystal display (LCD) device, and more particularly, to a thin-film transistor (TFT) LCD device designed such that defects in a pad portion can be easily repaired.
The present invention further relates to a method for repairing the defects in the pad portion.
2) Description of Related Art
Generally, a TFT LCD device typically includes a pair of substrates that are maintained in a spaced apart, yet parallel, relationship with one another. The space between the substrates is commonly referred to as the cell gap. Interposed between the substrates, within in the cell gap, is a liquid crystal material that changes its optical characteristics in response to an applied electrical signal.
On one of the substrates, a matrix of pixel electrodes are provided. The pixel electrodes are comprised of gate lines and data lines, the data lines being disposed vertically to the gate lines.
The TFT is provided on a side of the pixel electrodes to switch signals applied to each pixel electrode. In addition, source electrodes and gate electrodes of the TFT are connected to the data lines and the gate lines, respectively.
When one of the gate and data lines is broken, the signal is not fed to the broken line. The broken line causes deterioration in the quality of displayed images. Therefore, the broken line should be repaired. U.S. Pat. No. 4,807,973 to Kawasaki et al. discloses a matrix address display apparatus having a repair line for restoring the broken line. This patent will be described hereinafter with reference to FIGS. 1a and 1b. 
Referring first to FIG. 1, the apparatus comprises gate lines 1 and data lines 2, the data lines being disposed vertically (i,e.,perpendiculary) to gate lines 1. A plurality of display cells are formed on cross points of the gate lines 1 and the data lines 2, thereby making a pixel part. A closed repair line 7 is provided around the pixel part.
If one of the gate or data lines 1 or 2 is broken at a point 3, the repair line 7 is connected to both ends of the broken line by a conductive material 8. As a result, since the broken line is restored by the repair line 7 disposed around the pixel part, the signal can be fed to the broken line through the repair line 7.
FIG. 2 shows another embodiment of the patent. In this embodiment, two disconnection parts 6 are provided for dividing the repair line into two repair lines 7a and 7b. As a result of dividing the repair line, two lines broken at each of the broken points 3 can be respectively connected to the repair lines 7a and 7b by the conductive material. As a result, since both of the broken lines are restored by the repair lines 7a and 7b, respectively, the signal can be transmitted to the broken lines through the repair lines 7a and 7b. 
In the above described repair line structure of the liquid crystal display device, when the gate or data line is broken, this can be restored by the repair line. However, if a gate pad portion or a data pad portion is broken or defective, since the repair line structure is designed not to repair the broken pad portion, a pixel corresponding to the defective pad portion can not be excited.
Therefore, it is a first object of the present invention to provide a liquid crystal display device having a defective pad repair structure that can easily repair a defective pad.
It is a second object of the present invention to provide a method for making a defective pad repair structure.
To achieve the first object, the present invention provides a display device comprising a plurality of pads for inputting signals from a drive circuit to a plurality of drive lines, and means for, when at least one of contact the pads is defective, repairing the defective pad. The means comprises at least one pad repair line disposed to oppose ie., overlap the pads, and an insulating layer disposed between the at least one repair line and the pads.
Preferably, the pads are divided into a plurality of groups and the at least one pad repair line is provided for each group.
The pad repair line may be of a close-type crossing both ends of each of the pads.
The pad repair line may be of an open-type crossing both ends of each of the pads.
To achieve the second object, the present invention provides a method for forming a defective pad repair structure in a liquid crystal display device having a plurality of pads disposed on a substrate, the method comprising the step of forming at least one defective pad repair line to oppose the pads with an insulating layer disposed between the pads and the defective pad repair line, whereby when at least one of the pads is broken, the broken pad can be restored by connecting the broken pad to the repair line by a welding process.